If I play any game for around a minute (Minecraft or Crysis, doesn't matter) the screen will eventually be marred with some spatterings of purple or green pixels. Usually, these pixels are drawn in along contour lines withing the image currently being displayed.
Doing other things, like watching Hulu, won't mess up the computer, which leads me to believe I am only running into problems with things that run in 3d. My temperatures seem fine, around 65 F.
Maybe my Nvidia 8800 GT has begun to flip out, or at least I suspect that's what the problem is. I do have the most recent drivers... le sigh.
EDIT: Now the screen will be filled with any number of graphical wonders, and then throw my computer into a crash. Sometimes, I can recover from it with a quick leap to the task manager, but it is always crippled after the save.
Perhaps this is the universe's way of telling me I need to study for finals. Universe, just let me F*** my own life up, okay?!
Final update:
Yep, busted graphics card. Fortunately my dad had an untouched 9500 sitting in a drawer so I can get by for a while.